Being that this phone's dropped after only half a year, it's clear the people who care about this phone are very low... low enough to where T-Mobile should be open to simply unchaining people who bought it.

How can I carrier unlock this?

I've tried the live chat... they redirected me to a number that led me to multiple peoples that ultimately said they couldn't do anything about it. Tried many more times and finally was told that who I needed to speak to was a care specialist. They attempted to connect me and I was on hold for 2 hours then told there were no agents.

TMo customer service is pretty good with getting you an unlock code provided you meet the criteria - basically phone paid for and on-net for 40 days. You'll get an email in a couple of days with the unlock code. Note that you only get 3 tries to enter the unlock code into the handset and then it will brick I believe. Also, you need a "foreign" (non TMo) SIM in the handset when you power it up to get the phone to prompt for the unlock code. Good luck!